Climate Change and Agriculture

PIP COURTNEY, PRESENTER: Australia is a land of droughts, fires, storms and flooding rains, but if the climate science is right, the warning is to expect more of the same, but with more intensity and more often. The extensive bushfires and flooding across the east coast are potentially a snapshot of what's to come. But if that's the case, what's the impact on farmers and the future of agriculture in Australia? Here's environment reporter Sarah Clarke.

SARAH CLARKE, REPORTER: Everyone talks about the weather, but over the past 10 years that national conversation has increasingly focused on a changing climate. When the bush suffered its worst drought in a century, our big cities copped water restrictions. Climate scientists argue those record temperatures, destructive bushfires and wilder weather could be just a taste of the future.

MARK HOWDEN, CSIRO CLIMATE ADAPTATION FLAGSHIP: In particular, because we have likely increases in temperature, but also decreases in rainfall and a combination of those would tend to increase your drought periods, increase the dry spells that we experience and that will reduce productivity of our systems like we've seen over the last decade.

SARAH CLARKE: It's a scenario that's being closely studied by the CSIRO. In its most recent report it states that change is unavoidable. As well as hotter days and longer droughts, it says there's a chance of more extreme weather like cyclones, destructive storms and floods.

MARK HOWDEN: So, those sorts of floods and extremely wet events can also occur under those same scenarios. So we have an increase in both the dry end and the wet end, both of which impact on agriculture productivity.

SARAH CLARKE: Across Australia the impact of climate change will be variable. In parts of Queensland and NSW its predicted crop yields could fall and the quality of cotton will be affected. But fewer frosts may increase the types of crops that could be grown here. The centre is likely to experience the greatest warming. Grazing livestock, particularly cattle, will be stressed as a result and less likely to breed and irrigated cropping may also be challenged.

RICHARD KINGSFORD, UNIVERSITY OF NSW: Irrigation is so dependent on how much water is available and that means how much rainfall high up in the catchment, that's where most of the rainfall comes and how much of it is captured by the dams. So if we have much longer drought periods and very intense flood periods or rainfall periods, it's going to change that stability.

SARAH CLARKE: In the north the outlook is potentially wetter. In this region there's a 30 per cent chance rainfall will increase. If it does, a cotton industry could be an option and horticulture could expand. But flooding erosion and cyclones could also have devastating impacts. In this part of the country, the CSIRO forecasts all cropping could be hit by less rainfall. Having said that, some types could expand into areas currently too wet to farm.

STEVE CRIMP, CSIRO SENIOR RESEARCH SCIENTIST: Certainly across most of southern Australia the projections for the future are for warmer and dryer conditions. So when we're experiencing warmer and dryer conditions, particularly in those areas growing those crops, canola, wheat, barley, etc., will be more challenging in the future.

SARAH CLARKE: Steve Crimp has spent the last 15 years studying ways of helping farmers better adapt to a warming climate. He and his team are trying to identify not only crops that will cope, but farming methods.

STEVE CRIMP: What we've looked at is a range of different adaptation options, those include different crop varieties, different rotations and different land use and also looking at the different proportions of grazing and cropping on individual farms. And what we've looked at is we've looked at farms across the country and had a look at how effective those particular adaptation options are.

SARAH CLARKE: That includes the Murray-Darling Basin which produces around 40 per cent of the food in Australia. But how will it cope as temperatures heat up? The Federal Government's chief climate advisor spelt out the worst case scenario based on the science. By 2100, Ross Garnaut says irrigated agricultural production could fall by 92 per cent. Perhaps surprisingly, the final Murray-Darling Basin plan makes no mention of climate change.

RICHARD KINGSFORD: That was one of the major disappointments about the Basin plan. Their perception was that it would be possible to change the plan as we go through, but the modelling by CSIRO quite clearly shows that as the Murray-Darling Basin dries and we get less run off, that there's an inequitable sharing of that pain.

SARAH CLARKE: Like on land, the oceans too are being closely monitored. Every month for the last 70 years scientists have been recording temperatures at this station at Port Hacking off the NSW coast.

TIM INGLETON, NSW ENVIRONMENT OFFICE: They're able to record those temperatures, you know, a couple of times a second so we're getting four or five readings per metre of water depth. So we now have data being collected on every metre of water from the surface down to the bottom at each of those sites.

SARAH CLARKE: With that level of in-depth analysis, scientists are getting the most accurate snap shot of the state of the ocean and coastal temperatures. Apparently the East Coast is one of the fastest warming areas of Australia.

ALISTAIR HOBDAY, CSIRO MARINE RESEARCH: The background rate of ocean warming has been about 0.7 of a degree over the last hundred years. We've seen warming on the East Coast of Australia of a bit over two degrees in that same period of time.

SARAH CLARKE: As ocean temperatures rise, the CSIRO says the makeup of the marine ecosystem is also changing. Fish are heading south with the warmer waters, 45 species are moved into the Tasmanian region - that's about a third of the total fish in the area.

ALISTAIR HOBDAY: Recreational fishermen are very excited about some soft species that are moving into southern waters, including dolphin fish, tuna, bill fish as well as coastal species like snapper. For other fisheries, however, the news is less good and species like rock lobster will be more challenged by warming oceans. In particular as the ocean warms, their recruitment seems to decline, so there'll be less animals coming through for harvest.

SARAH CLARKE: Scientists are also recording marine heatwaves. This one off WA two years ago hit ocean temperatures up to five degrees above average over a two-week period. There was a mass fish kill, coral was lost and bleaching was recorded for the first time in the north-west region.

ALISTAIR HOBDAY: We expect those heatwave events to become more common in the ocean, but this was the most dramatic one we've observed in human history. Another result of that warming was a massive die off of abalone which has pretty much closed down an abalone fishery in that region and it will take some years to recover that by planting back adults that they hope will recover the stock.

SARAH CLARKE: But not everyone involved in Australian agriculture is convinced. A recent survey indicates that about 20 per cent of primary producers don't accept it.

MATT LINNEGAR, NATIONAL FARMERS' FEDERATION: I think like the rest of the Australian society there is a variety of views about climate change and what it means. But I can certainly tell you this: that farmers are probably more aware than most of current fluctuations and variations in climate and what it means for their business. They're at the cutting edge of that, if you like. So, you know, in that sense they're probably better prepared, you know, mentally and otherwise to deal with those sorts of challenges.

SARAH CLARKE: Regardless of farmers' beliefs on whether the climate is actually changing and what's causing it, scientists say the impacts will need to be managed.

MARK HOWDEN: What we probably will see is a change in agriculture so we won't necessarily do the same things in the same places, but I think we will see a strong continuation of agriculture across Australia. As I say, it may be different, but it will still be there.